1. Field of the Invention
The present invention relates to a stick-shaped material propelling container capable of propelling and retracting a stick-shaped material such as a stick-shaped eraser, a pencil lead, a crayon, a pastel and an eye brow stick.
2. Description of the Related Art
Heretofore, a stick-shaped material propelling container of this kind, are known from Japanese Utility Model Publication No. 3-44552 or Japanese Utility Model Publication No. 5-1426. In the stick-shaped propelling container disclosed in each of the documents, an inner barrel is slidably inserted in an outer barrel, and an elastic body which urges the inner barrel rearward is provided between the inner barrel and the outer barrel. Chuck pieces which hold the stick-shaped material are provided at a front end portion of the inner barrel, and a chuck ring is inserted between the chuck pieces and the outer barrel. The stick-shaped material can be propelled and retracted in response to the longitudinal sliding movement of the inner barrel relative to the outer barrel.
The conventional stick-shaped material propelling container is based on the premise that the cross-sectional shape of the stick-shaped material is circular, and when the tip end of the stick-shaped material, for example, a stick-shaped eraser is consumed and rounded, a delicate operation such as erasing of fine portions becomes difficult.
Thus, Japanese Patent Laid-Open No. 2006-335040 proposes a stick-shaped material propelling container suitable for causing the stick-shaped material to perform a delicate operation and capable of reliably holding the stick-shaped material.
In order to achieve a correct propelling operation of the stick-shaped material propelling container, a frictional force in a proper range has to be generated between the stick-shaped material and frictional force applying parts of the container for contacting with the stick-shaped material. The friction force is an important factor to stop return of the stick-shaped material. In the constitution disclosed in Japanese Patent Laid-Open No. 2006-335040 ribs as the friction force applying parts are formed on the inner peripheral surface of the outer barrel. The respective ribs contact with three vertexes of the stick-shaped material in the cross section.
When the ribs are brought into contact with the vertexes of the stick-shaped material in the cross-section, the dimension of a circumscribed circle connecting the vertexes in the cross section is important However, the dimension of the stick-shaped material is variable depending on conditions at the production and it is difficult to produce the stick-shaped material whose dimension of the circumscribed circle is very accurate. As a result, a problem is that the frictional force significantly changes due to the dimensional variation of the stick-shaped material up to exceed the proper range, whereby leading an operation failure that the stick-shaped material cannot be properly propelled.